1. Field of the Invention
The present invention relates generally to air filtration, and more particularly to air filtration that provides for improved fly ash and/or mercury emission control.
2. Discussion of the Prior Art
Air filters are known and used in many different applications, including use within filtration arrangements associated with combustion devices, such as coal-fired boilers. The air filters are capable of filtering particulate matter, such as fly ash, from combustion exhaust.
It is known that some combustion fuels, such as coal, include mercury (Hg). It is desirable to control the amount of mercury proceeding from a combustion device and through an air filter. It is known to add a sorbent, such as activated carbon, into the combustion exhaust gas in an effort to help entrap the mercury and thus remove the mercury from the combustion exhaust. However, there may be some aspects connected with the use of sorbent that are disfavorable, such as the cost of obtaining the sorbent.
In addition to a general desire to entrap mercury, there may also a desire to entrap mercury despite fluctuation of a concentration of mercury and/or other fluctuations that have an influence on the entrapment of mercury. Examples of such other fluctuations that have an influence on the entrapment of mercury may include variations in the fly ash in the combustion exhaust, gas chemistry within the combustion exhaust, combustion exhaust gas flow rate, filter media condition (e.g., deterioration thereof), dust-cake build-up, etc.
It would be beneficial to be able to control mercury entrapment in a desirable manner.